The invention pertains to an earth penetrating rotary drill bit that has a hard member at the axial forward end thereof. More specifically, the invention pertains to an earth penetrating rotary drill but that has a hard member at one end thereof and wherein the rotary drill bit contains debris (or dust) ports for evacuating dust and debris from the vicinity of the drilling operation.
The expansion of an underground coal mine requires digging a tunnel that initially has an unsupported roof. To provide support for the roof, an earth penetrating rotary drill bit (e.g., a roof drill bit) is used to drill boreholes, which can extend from between about two feet to about (or even greater than) twenty feet, into the earth strata. In this regard, the earth penetrating drill bit is connected to a drill steel. The drill steel is connected to a rotary driver. The rotary driver powers the earth penetrating drill bit so as to drill the earth strata. Roof bolts are affixed within the boreholes and a roof support (e.g., a roof panel) is then attached to the roof bolts. Examples of a conventional roof drill bit with an axial forward slot that carries a blade style hard insert are the KCV4-1RR and KCV4-1 1/32RR Roof Rocket™ drill bits made by Kennametal Inc. of Latrobe, Pa., USA and shown in U.S. Pat. No. 5,172,775 to Sheirer et al.
During the drilling operation, rotary drill bits generate debris. This debris can take the form of dust-like fine particles. The debris may also exist as larger particles. During the drilling operation, this debris is evacuated under the influence of a vacuum from the vicinity of the drilling operation through debris ports (or dust ports) contained in the body of the rotary drill bit. On occasion during the drilling operation, a rotary drill bit can generate a large enough volume of debris such that the rotary drill bit is unable to evacuate the debris quickly enough from the vicinity of the drilling operation to maintain the efficient operation of the rotary drill bit. When the debris cannot be adequately evacuated from the vicinity of the drilling operation, several consequences can occur.
One such consequence is that the speed at which the rotary drill bit operates, and hence the drilling rate, must be reduced so as to accommodate the debris. By reducing the speed of the rotary drill bit due to the inability of the rotary drill bit to evacuate debris, the operator is limited in being able to operate the rotary drill bit at its optimum capability. It would be desirable to provide an improved rotary drill bit that better evacuates drilling debris so as to enhance the ability of the rotary drill bit to operate at a higher speed.
Another such consequence of the inability to adequately evacuate debris from the vicinity of the drilling operation is that the rotary drill bit tends to stick in the bore hole. This causes the drilling operation to become less consistent and rougher. It would thus be advantageous to provide an improved rotary drill bit that better evacuates drilling debris from the vicinity of the drilling operation so as to provide for the smoother operation of the rotary drill bit.
Yet another such consequence of the inability to adequately evacuate debris from the vicinity of the drilling operation is that the rotary drill bit tends to overheat. This is due to the presence of drilling debris that increases the friction between the rotary drill bit and the earth strata (included the debris). It would thus be advantageous to provide an improved rotary drill bit that better evacuates drilling debris from the vicinity of the drilling operation so that the rotary drill bit operates cooler, i.e., operates at lower temperature.
Overall, it can be seen that there would be a number of advantages associated with being able to provide an improved earth penetrating rotary drill bit that is able to better evacuate debris from the vicinity of the drilling operation. The advantages include allowing for the rotary drill bit to smoothly operate at higher drilling rates and yet still be at a lower operating temperature.